How to Make It
Preheat the oven to 350°. Cut off the bulbous portion of the squash and reserve for another use. Using a mandoline adjusted to the thinnest setting, slice the neck of the squash lengthwise into long, thin ribbons.
Spread the walnuts in a pie plate and toast for about 6 minutes, until fragrant. Let cool slightly, then coarsely chop. Transfer the squash to a bowl, toss with the vinegar and season with salt and pepper. Lightly stir in the olive oil, prosciutto and walnuts, garnish with the Parmesan and serve.